[2] The remaining 12% is accounted for by lower-energy Auger electrons and a few photons from other, minor transitions.
The advantages of the emitted X-rays are that they are monochromatic and are continuously produced over a years-long period.
[4] The ExoMars mission of ESA used, in 2016,[5][6] such an iron-55 source for its combined X-ray diffraction/X-ray fluorescence spectrometer.
[7] The 2011 Mars mission MSL used a functionally similar spectrometer, but with a traditional, electrically powered X-ray source.
[11] People close to the test ranges, for example Iñupiat (Alaska Natives) and inhabitants of the Marshall Islands, accumulated significant amounts of radioactive iron.